So the basis of this bug is my colleague, a CAD designer documents his design process on our internal mediawiki. He spends a lot of time and effort creating these pages using VisualEditor (0.1.0). At a time he adds a lot of text from the process, but when required to add an image he must swap to edit source because our VisualEditor version does not allow uploading of local files. When he swaps from editing in VisualEditor to edit source he gets prompted with a window asking him if he meant to do this and will give him three choices on the matter:

a) didnt mean to(cancel)
b) yes he did mean to but discard all changes
c) yes he did and please save changes

Obviously having spend a substantial amount of time editing this document and needing to add the image files in to complete he selects option C. This leads to the whole wiki freezing and crash deleting all progress he made before he could even get into the edit source tab.

This is what makes me believe it is a bug within your extension.

Cheers for reading, please get back to me as soon as possible.